This invention relates to halogen containing polymer compounds. In particular, the invention relates to halogen containing polymers stabilized by modified zeolites. The modified zeolites have a small particle size, narrow particle size distribution, and a reduced water content. When incorporated into a halogen containing compound, the modified zeolites improve the processing stability of the compound and do not adversely diminish its physical properties. Furthermore, the invention relates to a halogen containing polymer compound stabilized by a modified zeolite and having improved processing stability. Moreover, this invention relates to a method of forming such a halogen containing polymer compound incorporating a modified zeolite therein.
Halogen containing polymers tend to degrade or deteriorate when processed. Generally, the difference between the processing temperature and the degradation temperature is very small. Therefore, there is a risk that during the processing of these halogen containing polymers, that the polymer will degrade. When such polymers degrade, it is believed that the halide acid generated by the polymer attacks the components of the processing equipment. Also, this acid further catalyzes elimination reactions and additional degradation of the polymer.
Stabilizers have been developed to help deter such degradation. For example, organic compounds are commonly used. In some instances, zeolites have also been used as stabilizers.
Zeolites are effective acid scavengers for halogen containing polymers and enhance the thermal stability of halogen containing polymers. Acid scavengers are compounds that react with acids to form a compound that is typically chemically inert. However, the use of zeolites as stabilizers or acid scavengers in halogen containing polymer compounds has been limited for several reasons. First, the zeolites generally have a large particle size, generally in the range of about 3 to about 6 microns. The large size of the zeolite particles not only causes surface blemishes on the finish of the end product made from such a polymer but also diminishes the physical properties of such polymers. Further, outgassing occurs frequently with polymers containing zeolites when the polymer is heated during processing due to the evolution of water from the zeolite during the heating. As a result, there is foaming.
U.S. Pat. No. 4,000,100 discloses a thermal and light stabilized polyvinyl chloride resin. The stabilizer used in the composition comprises an unactivated zeolite A molecular sieve or an unactivated naturally occurring molecular sieve of essentially the same pore size range as zeolite A and a conventional inorganic, organometallic or organic stabilizer. The unactivated zeolite molecular sieve has adsorbed water molecules. According to the patentee, the combination of the unactivated zeolite and the conventional stabilizer produces a compound with allegedly improved stability as compared to a compounds produced with either of the two stabilizers separately.
Similarly, U.S. Pat. No. 4,338,226 discloses a process for the stabilization of polyvinyl chloride and stabilizer compositions. The patent describes admixing sodium aluminosilicate of small particle size (preferably, 0.1 to 20 microns), calcium salts of fatty acids, zinc salts of fatty acids, partial esters of polyols and fatty acids, thioglycolic acid esters of polyols and polyvinyl chloride or copolymer of vinyl chloride. An aluminosilicate that can be used is crystalline sodium zeolite A. The composition is used for molding mixtures.
U.S. Pat. No. 4,371,656 describes a metal substituted zeolite for use as a stabilizer for halogen containing resins. The stabilizer comprises a crystalline aluminosilicate substituted with ions of metallic elements belonging to Group 11 or Group IVA of the Periodic Table for the Group I (M) metal ion contained in the aluminosilicate. The stabilizer also must contain 10% by weight or less as M2O of residual Group I metal ions. The stabilizer, zeolite A, according to the patentee claims to have a water content of 8% by weight or less. This patent also discloses the use of organic substances to cover the voids of the zeolite particles and prevent moisture reabsorption.
Stabilized chloride containing resins are also described in U.S. Pat. No. 5,004,776. The stabilizer consists essentially of: (a) an overbased alkaline earth metal carboxylate or phenolate complex; (b) zeolite; (c) calcium hydroxide; and (d) a complex of at least one metal perchlorate selected from the group consisting of sodium, magnesium, calcium, and barium perchlorates with at least one compound selected from the group consisting of polyhydric alcohols and their derivatives. This stabilizer apparently prevents the discoloration and deterioration in physical properties of the chlorine containing resin resulting from thermal degradation when the resin is subject to thermoforming or exposed to a high temperature atmosphere for a long period of time.
Stabilizer compositions for use in halogen containing polymer are also described in U.S. Pat. No. 5,216,058. The stabilizer composition comprises hydrotalcite and a molecular sieve zeolite. The molecular sieve zeolite comprises a Group IA or IIA aluminosilicate.
U.S. Pat. No. 5,582,873 discloses an acid scavenger stabilized halogen containing organic polymer. The patent also describes the method for processing such a polymer. The composition comprises a halogen containing polymer, an zeolite as the acid scavenger and a heat stabilizer selected from the group consisting of mixed metal stabilizers, organtotin stabilizers, lead stabilizers, metal free stabilizers or any combination thereof. The acid scavengers are sodium zeolites which have a 13 to 25% water content, and a mean particle size of about 3 to about 5 microns.
Thus, there currently exists a need for a halogen containing polymer compound having improved process stability. In particular, a need exists for a stabilizer for a halogen containing compound comprising a modified zeolite which maintains the physical properties of the halogen containing polymer. More particularly, a need exists for a modified zeolite stabilizer for use in chlorinated polyvinyl chloride and polyvinyl chloride compounds. More particularly, there exists a need for a chlorinated polyvinyl chloride compound which has improved processability including excellent heat stability.
The present invention comprises novel halogen containing compounds with improved process stability. These compounds are made from a halogen containing polymer and a modified zeolite. The modified zeolite has a small particle size, a narrow particle size distribution and a water content of less than 10 weight percent. Furthermore, the present invention also comprises a method of forming such a compound.
As described above, the present invention comprises a composition of a halogen containing polymer and a modified zeolite, wherein such modified zeolite imparts stability to the halogen containing polymer and widens the range of temperatures which can be used in the processing of such halogen containing compounds. When incorporated into the compound, the modified zeolite does not contribute to the deterioration of the physical properties of the compound.
Examples of possible halogen containing polymers that can be used in the instant invention include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, polyvinyl bromide, polyvinyl fluoride, polyvinylidene fluoride, copolymers of vinyl chloride with a copolymerizable ethylenically unsaturated monomer such as vinylidenechloride, vinyl acetate, vinyl butyrate, vinyl benzoate, diethyl fumarate, diethyl maleate, other alkyl fumarates and maleates, vinyl propionate, methyl acrylate, 2-ethylhexylacrylate, butyl acrylate, ethyl acrylate, and other alkyl acrylates, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, and other alkyl methacrylates, methyl alpha-chloracrylates, styrene, vinyl ethers such as vinyl ethyl ether, vinyl chloroethyl ether, vinyl phenyl ether, vinyl ketones such as vinyl methyl ketone, vinyl phenyl ketone, 1-fluoro-1-chloroethylene, acrylonitrile, chloroacrylonitrile, allylidene diacetate, chloroallylidene diacetate, ethylene and propylene and polymer blends such as blends of polyvinyl chloride and polyethylene, polyvinyl chloride and chlorinated polyethylene, polyvinyl chloride and polybutylmethacrylate and any combinations of the foregoing. The amount of the halogen containing polymer contained in the compound can range from about 70 to about 99 weight percent. However, the exact amount of the halogen containing polymer used in the compound is dependent upon its end use and is well within the purview of one of ordinary skill in the art.
Preferably, the halogen containing polymer is either polyvinyl chloride or chlorinated polyvinyl chloride. Most preferably, the halogen containing polymer is chlorinated polyvinyl chloride.
The polyvinyl chloride (xe2x80x9cPVCxe2x80x9d) which can be used in the present invention preferably has an inherent viscosity in the range of 0.52 to 1.0; a fused density of about 1.35 grams/cubic centimeter and a chlorine content of about 56.7%. The PVC resin can be formed by mass, suspension or emulsion polymerization techniques. Examples of suitable PVC resins which can be used to form the halogen containing compounds of the instant invention include Geon 103EPF76TR, 103 EPF76, 30, 110X440, 27 and 1023PF5 PVC; all available from The Geon Company.
The PVC polymers can be homopolymers or copolymers of polyvinylchloride. These polymers generally have a density of about 1.40 grams/cubic centimeter. Copolymers of PVC are formed predominately with PVC and other copolymers such as for example vinyl acetate. Generally, the secondary monomer is present in the range of five percent. A further discussion of PVC copolymers can be found in Volume 1 of Encyclopedia of PVC, edited by Leonard I. Nass, Marcel Dekker, Inc. (N.Y. 1976, Chap.4).
Alternatively, PVC compounds can also be used. Examples of suitable PVC compounds include: Geon M6215 and M6230 rigid injection molding PVC; Geon 85890 and 85891 cellular injection molding PVC; Geon 8700A, 8700x, 87256, and 87160 interior rigid extrusion PVC; Geon 87416, 87703 and 6935 exterior rigid extrusion PVC; and Geon 85893, 87344, 87345, 87538, 87695 and 87755 rigid powder extrusion PVC. The various grades of the Geon PVC are commercially available from The Geon Company.
The most preferred halogen containing polymer used in the compound of the instant invention is chlorinated polyvinyl chloride. Chlorinated polyvinyl chloride (xe2x80x9cCPVCxe2x80x9d) is known to have excellent high temperature performance characteristics, among other desirable physical properties. Typically, CPVC has an excess of 57% bound chlorine. CPVC is conveniently made by the chlorination of a polymer of vinyl chloride (PVC), which include both homopolymers and copolymers of vinyl chloride, having a chlorine content of up to 56.7%.
CPVC is obtained by chlorinating homopolymers or copolymers of PVC containing less than fifty percent (50%) by weight of one or more copolymerizable comonomers. Preferably, comonomers are not used. However, suitable comonomers include acrylic and methacrylic acids; esters of acrylic and methacrylic acid wherein the ester portion has from 1 to 12 carbons; hydroxyalkyl esters of acrylic and methacrylic acid (for example hydroxymethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate and the like); glycidyl ester of acrylic and methacrylic acid (for example glycidyl acrylate, glycidyl methacrylate and the like); alpha,beta-unsaturated dicarboxylic acids and their anhydrides (for example maleic acid, flimaric acid, itaconic acid and the like); acrylamide and methacrylamide; acrylonitrile and methacrylonitrile; maleimides; olefins (for example ethylene, propylene, isobutylene, hexene and the like); vinylidene halide; vinyl esters; vinyl ethers; crosslinking monomers (for example, diallyl phthalate, ethylene glycol dimethacrylate, methylene bis-acrylamide, divinyl ether, allyl silanes and the like).
Any post chlorination processes can be used to form CPVC polymer having more than fifty-seven percent (57%) by weight chlorine based upon the total weight of the polymer. Preferably, the CPVC polymer has a chlorine content in the range of about sixty percent (60%) to about seventy four percent (74%) by weight based upon the total weight of the polymer. The post chlorination processes which can be used include any commercial process or the like such as solution process, fluidized bed process, water slurry process, thermal process or liquid chlorine process or two step process which comprises post chlorinating the vinyl chloride polymer in the presence of a peroxy catalyst during both steps. In as much as the post chlorination processes are known to the art as well as the literature, they will not be discussed in detail here. Rather reference is hereby made to U.S. Pat. Nos. 2,996,049; 3,100,762; 4,412,898 3,532,612; 3,506,637; 3,534,013; 3,591,571; 4,049,517; 4,350,798; 4,377,459, 5,216,088 and 5,340,880 which are hereby fully incorporated by reference as to the method of forming CPVC by post chlorinating PVC. The preferred process in forming the CPVC from the PVC is the aqueous suspension process disclosed in U.S. Pat. No. 4,412,898.
In addition, blends of various CPVC resins can also be used. For example, the CPVC resin can be blended with PVC homopolymers or copolymers or with another CPVC resin in an amount of other resin of about 1 weight percent to about 50 weight percent. Additionally, the CPVC can also be blended from about 1 weight percent to about 50 weight percent with another other halogen containing polymer or polymers.
The CPVC used in the invention desirably will have a fused density in the range of approximately 1.38 to 1.65 grams/cubic centimeter at 25xc2x0 Centigrade, an inherent viscosity (I.V.) in the range of about 0.52 to about 1.0 and a chlorine content of at least sixty percent (60%). The preferred fused density of the CPVC resin is in the range of about 1.51 to about 1.65 grams/cubic centimeter. The preferred inherent viscosity is in the range of about 0.68 to about 0.92. The preferred chlorine content of the CPVC is about 63% to about 70.5%. Examples of suitable CPVC resins to use in forming the compound of the instant invention include TempRite(copyright) 677xc3x97670 CPVC, and TempRite(copyright) 674xc3x97571 CPVC, all available from The B.F. Goodrich Company. TempRite(copyright) is a registered trademark of The B.F. Goodrich Company. The most preferred CPVC resin is TempRite(copyright) 674xc3x97571 CPVC resin.
Alternatively, CPVC compounds can be used in the compounds of the compound of the instant invention. Examples of suitable compounds which can be used include the following TempRite(copyright) CPVC compounds: 3104, 3210, 88038, 3107, 3109, 3114, 88738, 3105, 3214, 88971, 88027, 3219, 3205, 3212, 3206, 88023, 88033, 88955, SP220, 88745 and 3207 CPVC compounds. TempRite(copyright) is a registered trademark of The B.F. Goodrich Co. The above enumerated compounds are all commercially available from The B.F. Goodrich Co. in Cleveland, Ohio. The most preferred CPVC compound used in the instant invention is TempRite(copyright) 3104 CPVC compound.
The halogen containing polymer is stabilized by an effective amount of a modified zeolite. The modified zeolite should have a narrow particle size distribution, small particle size, and a reduced water content. Preferably, the zeolite should have a mean particle diameter in the range of about 0.25 to about 1.5 microns, a  less than 90% value particle diameter (90% by weight of the particles are of a particle diameter below the range) of about 0.30 to about 3 microns, and a water content of less than 10 weight percent.
Zeolites comprise basically of a three dimensional framework of SiO4 and AlO4 tetrahedra. The tetrahedra are crosslinked through the sharing of oxygen atoms so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms it equal to 2. This relationship is expressed as O/(Al+Si)=2. The electrovalence of the tetrahedra containing aluminum and silicon is balanced in the crystal by the inclusion of a cation. For example, the cation can be an alkali or alkaline earth metal ion. The cation can be exchanged for another depending upon the final usage of the aluminosilicate zeolite. The spaces between the tetrahedra of the aluminosilicate zeolite are usually occupied by water. Zeolites can be either natural or synthetic.
The basic formula for all aluminosilicate zeolites is represented as follows:
M2/nO:[Al2O3]x:[SiO2]y:[H2O]z
wherein M represents a metal, n represents the valence of the metal and X and Y and Z vary for each particular aluminosilicate zeolite. Essentially it is believed that any aluminosilicate zeolite can be used as a stabilizer in the instant invention, provided that the ratio of the silicon to aluminum in such aluminosilicate zeolite is less than 3.0 and that the aluminosilicate zeolite can be incorporated into the halogen containing polymer. Preferably, the zeolite ratio of silicon to aluminum in such aluminosilicate zeolite is less than 1.5. Most preferably, the ratio of silicon to aluminum in such aluminosilicate zeolite is about 1.
It is further believed that the following zeolites which can be used in the instant invention include but are not limited to zeolite A, described in U.S. Pat. No. 2,822,243; zeolite X, described in U.S. Pat. No. 2,822,244; zeolite Y, described in U.S. Pat. No. 3,130,007; zeolite L, described in Belgian Patent No. 575,117 zeolite F, described in U.S. Pat. No. 2,996,358; zeolite B, described in U.S. Pat. No. 3,008,803; zeolite M, described in U.S. Pat. No. 2,995,423; zeolite H, described in U.S. Pat. No. 3,010,789; zeolite J, described in U.S. Pat. No. 3,011,869; and zeolite W, described in U.S. Pat. No. 3,102,853.
The preferred zeolites include alone or in combination with another Group I metal, hydrated silicates of aluminum incorporating sodium, of the type mNa2O.xAl2O3.ySiO2.zH2O. These preferred zeolites include zeolites A, X, and Y. The most preferred zeolite is zeolite 4A. Zeolite 4A, preferably has the following formula:
M2/nO:[AlO2]12:[SiO2]12:[H2O]27
wherein M is sodium. Any method can be used to form such zeolite provided that the mean particle diameter of the zeolite is less than 1.5 microns, and  less than 90% value particle diameter of about 0.30 to about 3 microns. Furthermore, when modified, this zeolite must have a water content of less than 10 weight percent and should provide for improved process stability when incorporated into a compound.
For example, a relatively simple process can be used to prepare the zeolite of the instant invention. First, the zeolite is synthesized. The exact synthesis will vary dependent upon the specific zeolite being used; this synthesis is well within the skill of one of ordinary skill in the art. Generally, however, a mixture of the aqueous solution of the materials which can be represented as mixtures of oxides, Na2O; Al2O3; SiO2 and H2O are reacted at a temperature in the range of about 50xc2x0 C. to about 100xc2x0 C. for a period of about 45 minutes to about 2000 minutes. Alternatively, the mixture of the reactants are allowed to age from about 0.1 to 48 hours at ambient conditions prior to the crystallization step. Preferably, the temperature of the reaction is in the range of about 50xc2x0 C. to about 80xc2x0 C. and the reaction is carried out for about 60 to 420 minutes. Most preferably, the temperature is 60xc2x0 C. to 70xc2x0 C. with a reaction of time of 90 to 300 minutes. The result of this reaction is a zeolite having a mean particle diameter in the range of about 0.25 to 1.5 microns. The  less than 90 percent particle diameter value is in the range of about 0.30 to about 3.0 microns.
After the zeolite is formed, it is washed. The zeolite can be washed with deionized water, filtered and dried at about 100 to about 200xc2x0 C., then dehydrated at about 250 to about 500xc2x0 C. Any means available to dehydrate the zeolite can be used. It is believed that the zeolite has better reproductivity if dried. For example, the zeolite can be furnace dehydrated. If furnace dehydrated, any suitable furnace can be used provided that the desired temperature can be reached. Generally if furnace dehydrated, the zeolite is heated to approximately 250 to about 500xc2x0 C. for about 2 to 6 hours. Alternatively, the small particle size zeolite can be dehydrated in vacuo at approximately 200xc2x0 C. for about 2 to about 6 hours.
These aluminosilicate zeolites are then modified. The modified aluminosilicate zeolite has a water content of less than 10 weight percent. Any method which decreases the water content of the aluminosilicate zeolite can be used. For example, the aluminosilicate zeolite can be modified by chemically altering the surface of the zeolite particles, shock annealing or by a coating or by a combination of shock annealing and coating processes. The purpose of the modification is to prevent the aluminosilicate zeolite particles from absorbing water but still allowing the zeolite particles to react with the acid released upon the deterioration or degradation of the halogen containing polymer. If CPVC is the polymer used in the halogen containing compound, preferably, the water content of the modified aluminosilicate zeolite is less than 8 weight percent.
Any organic, inorganic or low molecular weight ( less than 10,000) coating or coating mixture can be used provided that it has the following characteristics. First, in the case of inorganic coatings, they cannot be redox active; namely, the composition should have its d shell filled. Second, the coating cannot be water soluble or water permeable. Third, the coating should be reactive or permeable to the halogen acid. Fourth, the coating should not be a Lewis Acid. Preferably the coating used is miscible with the halogen containing polymer. Examples of suitable coatings include oxides such as magnesium oxide, paraffin waxes, low molecular weight organic matrices such as calcium stearate, high molecular weight matrices such as siloxanes, acrylic polymers such as methacrylate polymers. Preferably the coating is either dibutyl tin thioglyocalate or polydimethysiloxane.
The coating can be prepared in situ during the formation of the zeolite particles or applied to the zeolite particles in a separate step. If applied in a separate step, care should be taken to ensure the uniform application of the coating as well as to avoid clumping. Furthermore, the coating cannot be too thick or too thin, therefore, a balance must be obtained so as to ensure low water absorption but retain activity of the zeolite particles as acid scavenger.
Alternatively, the zeolite particles can be modified by shock annealing the particles. With the use of a shock annealing process for the zeolite particles, a phase transformation occurs at the outer surface of the zeolite particle shell. It is believed that the phase transformation causes the collapse of the zeolite structure at the outer surface. The shock annealing occurs at a temperature above the phase transformation temperature of the zeolites followed by rapid cooling. The shock annealing is carried out for the appropriate time to cause the outer surface of the particles to collapse. Exposure time to this temperature above the phase transformation temperature is however limited to minimize the bulk absorption of thermal energy and to limit the phase transformation to the outer surface of the particles. The temperature at which the zeolite is heated during the shock annealing process is dependent upon the particular zeolite being shock annealed. The temperature as well as the time to shock anneal is well within the skill of one of ordinary skill in the art.
One method to shock anneal the zeolite particles is disclosed in the copending application filed by the instant inventors, entitled xe2x80x9cZeolites and Method of Making Thereofxe2x80x9d, filed concurrently herewith. The contents of the application are incorporated in its entirety herein.
As described in the copending application, the zeolite particles are then placed in a furnace during the shock annealing step. Preferably, the particles are placed in a preheated crucible which can be made from quartz, high temperature steels or aluminum oxide. The crucible with the particles are returned to a muffle furnace. Any furnace can be used so long as it reaches the desired temperature. In the most preferred embodiment, an aluminum oxide crucible is preheated to approximately 700 to 1200xc2x0 C. prior to the addition of the small particle size zeolite.
Once the zeolite is added, it is heated about 1 to about 30 minutes in the temperature range of about 700 to about 1200xc2x0 C. After the zeolite particles are heated, as set forth in further detail in the copending application, they are cooled. Any cooling means can be used so long as the temperature is cooled below the phase transformation temperature in a matter of seconds, for example, about 600xc2x0 C. for zeolite 4A. Therefore, the particles can be cooled by air, water, carbon dioxide or liquid nitrogen.
Alternatively, the zeolite particles can be modified by both shock annealing and coating. If such a combination method is used to modify the zeolite particles, they are first shock annealed to within 15 to 10 percent of the desired optimum properties and then coated. By using both a coating and the shock annealing step, it may be possible to use other coatings which do not meet all the listed parameters set forth above with respect to the coatings.
The amount of the modified zeolite added to the halogen containing polymer to form the compounds of the instant invention is generally in the amount of about 0.05, 0.1, 0.2, 0.25, 0.3, 0.5, 0.75, or 1 to about 10 per one hundred parts of halogen resin used in the compound. Most preferably, the amount of modified zeolite added to the compound is in the range of about 0.1, 0.2, 0.3, 0.4 to 7 weight percent of the compound. By adding the zeolite to the compound, the dynamic thermal stability of the compound as measured by ASTM D 2538 is increased from 10% to 300% compared to a control compound without zeolite. Additionally, by adding the zeolite to the compound a reduced amount of thermal stabilizer is needed to maintain or increase dynamic thermal stability when compared to a compound not containing the zeolite.
In addition to the halogen containing polymer and the modified zeolite stabilizer, other ingredients typically added to halogen containing polymers can be included in the compounds of the instant invention. The amount and nature of these ingredients is dependent upon the end use of the halogen containing polymer. The ingredients and their amount can be tailored to meet the end-use needs by one of ordinary skill in the art.
For example, other stabilizers can also be used in conjunction with the modified zeolite stabilizer in the halogen containing polymer of the instant invention depending upon the halogen polymer used. Examples of possible stabilizers to use in halogen containing polymers include tin stabilizers, lead stabilizers, as well as stabilizers containing lithium, sodium, potassium, magnesium, calcium, strontium, barium, zinc, cadmium, aluminum, lead and antimony. Many of these enumerated stabilizers fall into a group of stabilizers called metal soap stabilizers. Metal soap stabilizers are metal carboxylates wherein the carboxylic acid typically has a chain length of 8 to 18 carbon atoms. Metal soap stabilizers can also include mixed metal soaps stabilizers. Examples of some mixed metal soap stabilizers include barium/cadmium, barium/cadmium/zinc, barium/zinc, barium/tin, barium/lead, cadmium/zinc, calcium/zinc, calcium/zinc/tin, strontium/zinc.
Suitable tin stabilizers include tin salts of monocarboxylic acids such as stannous maleate. Examples of tin stabilizers include without limitation: alkylstannoic acids, bis(dialkyltin alkyl carboxylate)maleates, dialkyltin bis(alkylmaleates), dialkyltin dicrotonates, dialkyltin diolates, dialkyltin laurates, dialkyltin oxides, dialkyltin stearates, alkylchlorotin bis(alkylmercaptides), alkylchlorotin bis(alkylmercaptopropionates), alkylthiostannoic acids, alkyltin tris(alkylmercaptides), alkyltin tris(alkylmercaptoacetates), alkyltin tris(alkylmercaptopropionates), bis[dialkyl(alkoxycarbonylmethylenethio)tin]sulfides, butyltin oxide sulfides, dialkyltin bis(alkylmercaptides), dialkyltin bis(alkylmercaptoacetates), dialkyltin bis(alkylmercaptopropionates), dialkyltin xcex2-mercaptoacetates, dialkyltin xcex2-mercaptoacetates, dialkyltin xcex2-mercaptopropionates, dialkyltin sulfides, dibutyltin bis(i-octyl maleate), dibutyltin bis(i-octyl thioglycolate), dibutyltin bisthiododecane, dibutyltin xcex2-mercaptopropionate, dimethyltin bis(i-octyl thioglycolate), dioctyltin laurate, methyltin tris(i-octyl thioglycolate). Examples of a commercially available tin stabilizer are Mark 292 and Mark 1900 stabilizers from Witco Chemical and Thermolite 31 stabilizer from Elf Atochem.
Lead stabilizers can also be used in the halogen containing compounds of the instant invention. Examples of lead stabilizers are dibasic lead stearate, tribasic lead stearate, dibasic lead phthalate, tribasic lead phosphite, basic lead silico-sulfate, tribasic lead sulfate, tetrabasic lead sulfate and lead carbonate.
Other co-stabilizers may be included in the compounds with the stabilizers if such stabilizers are used in addition to the modified zeolite stabilizer, and if desired, but are not necessary. However, if a solid co-stabilizer is added, the particle size of the co-stabilizer must be small enough so as not to affect the impact properties of the compounds described herein. Examples of co-stabilizers include metal salts of phosphoric acid, polyols, epoxidized oils, beta-diketones and acid acceptors which are not detrimental to the base halogen containing polymer used. The stabilizers can be used by themselves or in any combination as desired. Specific examples of metal salts of phosphoric acid include water-soluble, alkali metal phosphate salts, disodium hydrogen phosphate, orthophosphates such as mono-,di-, and tri-orthophosphates of said alkali metals, alkali metal polyphosphates, -tetrapolyphosphates and -metaphosphates and the like. Polyols such as sugar alcohols, and epoxides such as epoxidized soya oil can be used. Examples of possible acid acceptors include potassium citrate, aluminum magnesium hydroxy carbonate hydrate. An example of commercially available aluminum magnesium hydroxy carbonate hydrate is Hysafe 510, available from the J.M. Huber Company.
Chlorinated polyethylene (CPE) can also be added to the halogen containing polymer compound stabilized by the modified zeolite. The CPE is a rubbery material resulting from the chlorination of polyethylene having a substantially linear structure. The polyethylene can be chlorinated by various methods including aqueous suspension, solution or gas phase methods. An example of a method for preparing CPE can be found in U.S. Pat. No. 3,563,974. Preferably, the aqueous suspension method is used to form the CPE. If used as an impact modifier, the CPE material contains from 5 to 50% by weight of chlorine. Preferably, the CPE contains from 25 to 45% by weight of chlorine. However, the CPE can comprise a mixture of chlorinated polyethylenes, provided that the overall mixture has a chlorine content in the range of about 25 to 45% by weight chlorine. CPE is commercially available from The DuPont Dow Elastomer Company. The preferred CPE materials to be used in the compound include Tyrin 3611P, Tyrin 2000 and Tyrin 3615P; all available from the DuPont Dow Elastomer Company. Tyrin is a trademark of the DuPont Dow Elastomer Company.
The modified zeolite stabilized halogen containing polymer compound may also include acrylic impact modifiers. U.S. Pat. No. 3,678,133 describes the compositions conventionally referred to as acrylic impact modifiers. Generally, the acrylic impact modifier is a composite interpolymer comprising a multi-phase acrylic base material comprising a first elastomeric phase polymerized from a monomer mix comprising at least 50 wt. % alkyl methacrylate having 1-4 carbon atoms in the alkyl group and having a molecular weight of from 50,000 to 600,000. Further, the patent states that the polymerization of the rigid thermoplastic phase is preferably conducted in such a fashion that substantially all of the rigid phase material is formed on or near the surface of the elastomeric phase. Acrylic impact modifiers are polyacrylates including (C4-C12) acrylate homo or copolymers, second stage graft copolymerized with methyl methacrylate and styrene, poly(ethylhexyl acrylate-co-butyl-acrylate) graft copolymerized with styrene, and/or acrylonitrile and/or methyl methacrylate; polybutyl acrylate graft polymerized with acrylonitrile and styrene. Examples of suitable acrylic impact modifiers include Paraloid EXL-2330, KM 330, KM 334, and KM 365; all of which are available from Rohm and Haas. Paraloid is a trademark of the Rohm and Haas Company. Additionally Durastrength 200, available from Elf Atochem, and Kane Ace FM-10 and Kane Ace FM-25, available from Kaneka, are examples of commercially available acrylic impact modifiers.
Methyl butadiene styrene (xe2x80x9cMBSxe2x80x9d) impact modifiers can also be added to the compounds of the present invention. MBS polymers are graft polymers. Generally, MBS impact modifiers are prepared by polymerizing methyl methacrylate or mixtures of methyl methacrylate with other monomers in the presence of polybutadiene or polybutadiene-styrene rubbers. Further information on MBS impact modifiers can be found in the Second Edition of the Encyclopedia of PVC, edited by Leonard I. Nass, Marcel Dekker, Inc. (N.Y. 1988, pp. 448-452). Examples of commercially available MBS impact modifiers include Paraloid KM 680, BTA 733, BTA 751, BTA 753 available from Rohm and Haas, Kane Ace B-22 impact modifier and Kane Ace B-56 impact modifier available from Kaneka.
Other additives can also be added to the halogen containing polymer compounds as needed. Conventional additives known in the art as well any other additives may be used, provided that the additive does not alter the physical properties and the process stability associated with the novel compounds. Examples of additives which can be used include antioxidants, lubricants, other stabilizers, other impact modifiers, pigments, glass transition enhancing additives, processing aids, fusion aids, fillers, fibrous reinforcing agents and antistatic agents. The amount and nature of the additives incorporated into the halogen containing compounds stabilized by the modified zeolite is well within the skill of one of ordinary skill in the art.
Exemplary lubricants are polyglycerols of di- and trioleates, polyolefins such as polyethylene, polypropylene and oxidized polyolefins such as oxidized polyethylene and high molecular weight paraffin waxes. Since several lubricants can be combined in countless variations, the total amount of lubricant can vary from application to application. Optimization of the particular lubricant composition is not within the scope of the present invention and can be determined easily by one of ordinary skill in the art. Preferably, an oxidized polyethylene is used. An example of an oxidized polyethylene is AC 629A, sold by Allied Signal. In addition to the oxidized polyethylene, preferably a paraffin wax is also included in the compounds of the instant invention. An example of a paraffin wax is Paraffin 160F Prill from Witco.
Suitable processing aids include acrylic polymers such as methyl acrylate copolymers. Examples of process aids include Paraloid K-120ND, K-120N, K-175; all available from Rohm and Haas. A description of other types of processing aids which can be used in the compound can be found in The Plastics and Rubber Institute: International Conference on PVC Processing, Apr. 26-28 (1983), Paper No. 17.
An example of antioxidants to be used in the halogen containing compounds include Irganox 1010 (tetrakis[methylene(3,5-di-tert-butyl-4-hydroxy-hydrocinnamate)]methane) sold by Ciba, if used at all.
Suitable pigments include among others titanium dioxide, and carbon black. Examples of titanium dioxide is Tiona RCL-6 and RCL-4 from Millenium Inorganics. An example of carbon black is Raven 410, available from Columbian Chemicals.
Suitable inorganic fillers include talc, clay, mica, wollastonite, silicas, and other filling agents.
The components of the unique compound can be made in any manner wherein the various components are added together and mixed under heat. For example, the appropriate amount of the halogenated resin or halogen compound can be added to a vessel such as Henschel mixer or a ribbon blender. The remaining ingredients of the compound can then be added thereto and mixed until the blend is homogeneous. If pellets are to be formed, the compound can be melt mixed. Melt mixing can generally occur in the temperature range of about 150 to about 250xc2x0 C., if CPVC is the halogenated resin used as the base polymer to form the instant compound. Once the blend is formed, it can be processed further depending upon the desired application in any conventional manner, using extrusion or molding techniques.
If extrusion techniques are used to process the composition of the present invention, generally conventional extrusion machinery such as a multi-screw extruder or a single screw extruder are used. An extruder generally has conveying means, an intermediate screw processing means and a final die through which the material is discharged in the form of an extrudate. Generally, a multi-screw extruder is used for the extrusion of pipe. Examples of possible conventional extruders to be used to process the CPVC and PVC compounds containing the modified zeolite include the following twin screw counterrotating extruder models from Cincinnati Milacron: CM 35HP, CM 55HP, CM 65HP, CM 80HP, CM 92HP. Examples of suitable conical twin screw extruders from Krauss Maffei include KMD-2/40KK and KMD-2/50KK.
If the halogen containing polymer compound contains CPVC and is made according to the instant invention, it has the following characteristics: a tensile strength in the range of about 5,000 to about 10,000 psi (as measured according to ASTM D 638-95); a Notched Izod in the range of about 1.0 to about 20 ft.lb. per inch of notch (as measured according to ASTM D 256-93A); a dynamic thermal stability in the range of about 10 to about 60 minutes as measured by ASTM D 2538); a heat distortion temperature in the range of about 80 to about 140xc2x0 C. (as measured by ASTM D 648-95). Generally, the compound containing the modified zeolite maintains approximately 90% of its physical properties as compared to the same compound without the modified zeolite. This novel compound can be formed into any article desired. Examples include but are not limited to sheet, pipe, ducts, fittings, valves, injection molded and thermoformed industrial parts, appliance housing, fabricated parts, and different containers.